For a one-shot deal, it's hard to beat a large size styrofoam cooler with the SAME water the fish is taken out of (never do a drastic/different water quality change). Then add ice gradually to lower the metabolism rate. A simple, battery operated aquarium bubbler will enhance their survival rate. Like I said.....this is a "one-shot" deal ONLY. Don't plan on being successful doing this long term. For that, you need better equipment. If you win a tournament or two, it would be a good investment to get into a better system. JMO.
"A voyage in search of knowledge need never abandon the spirit of adventure."